Correction: An earlier version of this story incorrectly said that the bluefin population in the western Atlantic Ocean is at 36 percent of the 2012 level. It is at 36 percent of the 1970 level. The article also incorrectly described an international agreement limiting the U.S. bluefin catch for 2013. The limit of 950 metric tons is on the total catch, not just bycatch. This version has been corrected.

Workers at a fish market in Jersey City cut a bluefin tuna into pieces in order to provide it to New York’s top sushi restaurants. (EMMANUEL DUNAND/AFP/Getty Images)

Pity, for a moment, the poor Atlantic bluefin tuna. It’s not bad enough that its population has been decimated by diners’ seemingly insatiable appetite for sushi. Or that the 2010 Deepwater Horizon oil spill occurred at the height of its spawning season, in its only known Western spawning grounds.

No, bluefin also are plagued by another long-standing problem: They are inevitably caught by long-line fishermen trying to hook bigger, healthier schools of yellowfin tuna, swordfish and big-eye tuna. Under government regulations, the fishermen are allowed to bring a small number of the carefully regulated and valuable fish to shore for sale, but most of them die on hooks hanging from 20-mile fishing lines and are discarded at sea.

“No one wants to interact with bluefin,” said Terri Beideman, executive director of the Blue Water Fishermen’s Association, which represents about 120 tuna fishing vessels, most of them mom-and-pop operations. “They come onto your gear accidentally. No one is targeting them.” By one estimate, 111 metric tons of bluefin were killed this way in one year.

Now, the National Marine Fisheries Service (NMFS), the U.S. government agency that regulates offshore fishing, has waded into the controversy. It is proposing a complicated new plan designed to reduce the number of bluefin that long-liners inadvertently snare. The fish has been intensively managed for more than two decades, officials said, but the regulations need updating, in part to help reduce bycatch.

Under the proposal, the NMFS would sharply cut back the number of bluefin tuna that individual fishing vessels are allowed to capture accidentally, setting a quota for each boat and requiring fishermen to include the bluefin they discard at sea under that cap. The NMFS also would change the long-standing formula by which it calculates the number of pounds of bluefin tuna that a long-liner may legally bring to shore for sale.

Any vessel that exceeds its cap for accidentally caught bluefin wouldn’t be able to leave the dock to fish for other species, according to the proposal. Cameras and human observers on board the fishing boats would monitor compliance.

The idea, said Margo Schulze-Haughen, chief of the NMFS’s highly migratory species management division, is to provide an economic disincentive to hook bluefin tuna.

We “give them the amount of bluefin per year,” she said. “Then they have to manage it.

“Fishermen that are either ­unable or unwilling to avoid bluefin, I think they will have some difficulty,” Schulze-Haughen said. “But our analysis shows that three-quarters of the fleet will get an allocation that will enable them to continue fishing as they have.”

Beideman said her group is still working on its response to the proposed rules, which are open for public comment until Dec. 10. But she said she knows this: If the fleet that puts the vast majority of yellowfin tuna and swordfish on American plates is to survive, it needs greater bluefin quotas than the NMFS is proposing. Since bluefin swim with yellowfin, catching them is sometimes unavoidable, she and others have said, despite fishermen’s best efforts.

In some cases, Beideman said, a vessel would be allowed only a ton or so of bluefin bycatch — perhaps four or five large, mature fish — in a year. A few accidentally caught bluefin could easily cause that vessel to exceed its cap and end its fishing season early.

“If people are closed even three months early, they may not be able to get by until the next season,” she said. Few of the bluefin tuna sold by the vessels in her association are whisked to Japan for the high-quality sushi demanded there, and do not command the $10 per pound sometimes paid for the fish’s buttery flesh.

“That’s a big sea change, a big, new, revolutionary way to manage this fishery,” Beideman said. Long-liners “need more time, need more flexibility.”

The NMFS says it has a plan that would help. Under an international agreement, U.S. fishermen are limited to a total bluefin catch of 950 metric tons for 2013, distributed among seven categories of anglers, including those who use harpoons, rod and reel, and other gear that yields less bycatch. The agency would take 62.5 metric tons away from such hand-gear fishermen and redistribute it among long-liners, raising each boat’s individual quota.

“We’re furious about it, of course,” said Rich Ruais, executive director of the American Bluefin Tuna Association, which represents the hand-gear group. “These allocations, the current shares started in 1981. . . . We think the agency is making a monster mistake to try to change it around.”

“They’re on the right track,” said Lee Crockett, director of the nonprofit organization’s U.S. oceans program. “There’s a number of good things in this rule.”

The plan sets aside a 20,500-square-mile swath of the bluefin’s Gulf of Mexico spawning grounds for fishing by hand gear only, but Crockett said that restriction should be extended to the entire gulf. The group also wants the rule applied for March in addition, as the government proposes, to April and May.

The organization sponsored research into fishing with equipment that does not leave bluefin dangling for hours on long-line hooks, which stresses and often kills them, and has concluded that the alternatives work, Crockett said.

The bluefin, which can run several hundred pounds, “really need to swim so water goes through their gills,” he said. “These fish are the Ferraris of the ocean. It’s like you’re putting them on Logan Circle and they’re driving around in a circle.”

Pew also wants an area off North Carolina closed to long-liners from December to April, when the bluefin are migrating, and does not agree with transferring quotas from hand-gear fishermen to long-liners, Crockett said.

Lenny Bernstein writes the To Your Health blog. He started as an editor on the Post’s National Desk in 2000 and has worked in Metro and Sports.

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